It is well known in the art to optically analyze an object (hereinafter also referred to as a sample) by means of optical microscopy. However, the resolution of optical microscopy is limited due to the wavelength of the light used. The resolution achieved is in the range of a hundred to a few hundred nanometers.
A particle beam device for analyzing an object such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) has a better resolution than a device of optical microscopy above mentioned. Therefore, analysis by using a particle beam device is preferred if a high resolution in the range of a few nanometers is required.
U.S. Pat. No. 4,440,475 discloses an electron probe microanalyzer which is combined with an optical microscope. Therefore, an object can be analyzed by means of the electron probe microanalyzer as well as by means of the optical microscope.
One important role of today's science is the examination of biological cells and tissues as well as of diverse objects in today's life sciences. This examination is often carried out by way of optical microscopy and by way of a TEM. A light microscope, for example, is used to examine those objects which may include cells, acellular material and layers of tissue. A TEM is often used for obtaining subcellular information. However, both techniques have their limitations. On the one hand, optical microscopy is limited as to resolution as mentioned above. On the other hand, preparation of the objects for a TEM examination is rather difficult since the objects have to be very thin. Preparation of these objects requires special skills and often takes a few days to achieve.
Using a SEM is often easier since objects to be examined can be of any thickness. However, objects must be placed in a vacuum environment to allow unimpeded motion of the electron beam of the SEM. Therefore, the object to be examined should be dehydrated and dried. Accordingly, it is somewhat difficult to examine biological objects or wet objects with a SEM.
A device for the examination of samples, in particular wet samples in a non-vacuum environment using a SEM, is known in the prior art. The prior art discloses an object chamber (holding element) comprising at least one aperture sealed with a membrane. The membrane is adapted to withstand pressure gradients resulting from the presence of a vacuum and is transparent to electrons. The interior of the object chamber is isolated from the vacuum. The object chamber facilitates the examination of wet objects including living cells by placing the object chamber into the vacuum sample chamber of a SEM. After the object chamber is placed in the vacuum sample chamber, a vacuum is created in the latter. WO 02/45125 A1, WO 03/104848 A2, WO 03/104846 A2, WO 2004/075209 A1 and WO 2006/021961 are prior art with respect to the object chamber described.
However, the above mentioned known device has the disadvantage that the exchange of objects takes a rather long time since various steps have to be taken: First, the object must be placed into the object chamber which has to be positioned in turn into the vacuum sample chamber of the SEM. Moreover, the vacuum sample chamber has to be evacuated which normally takes 3 to 5 minutes since the vacuum sample chamber normally comprises a volume of approximately 300 mm×300 mm×300 mm.
Therefore, it would be desirable to provide a beam device comprising a means to simplify the exchange and to reduce the time of the exchange of an object to be examined.